Drop an inflatable tube into the hole. Try to maneuver the deflated tube under the dog. Inflate the tube and pull the dog up, using the tube as the "floor of th

Drop an inflatable tube into the hole. Try to maneuver the deflated tube under the dog. Inflate the tube and pull the dog up, using the tube as the "floor of the elevator" (so to speak). You could drop one of those auto-inflating life vests into the hole on a string, get it under the dog, then pull another string to inflate the jacket, then pull up the dog on the life jacket. I'm pretty sure you could get a vest large enough that it would block the hole!